1. Field of the Invention
The present invention relates to coating and developing treatment method and system for a substrate.
2. Description of the Related Art
In photolithography of the process of fabricating a semiconductor device, for example, resist coating treatment for forming a resist film on the surface of a wafer, developing treatment for developing the wafer after pattern exposure, heat treatment and cooling treatment performed before the coating treatment, before and after exposure processing, and after the developing treatment, and the like are performed. Such treatment and processing are performed in treatment units provided individually, and these treatment units are unified as a coating and developing treatment system so as to continuously perform the aforesaid successive treatment and processing. The exposure treatment of a pattern is usually performed in an aligner disposed adjacent to the coating and developing treatment system.
When the wafer is treated in this coating and developing treatment system, air cleaned by an air cleaner or the like, for example, is supplied as down-flowing air into the coating and developing treatment system in order to prevent impurities from adhering to the wafer, while an atmosphere in the coating and developing treatment system is exhausted, whereby the wafer can be treated in a clean condition.
In recent years, however, exposure technology in which a beam with a shorter wavelength (for example, 157 nm) is used is being developed to form a finer and more precise circuit pattern. When the beam with the short wavelength is used, there is a fear that even impurities at molecular level such as oxygen, ozone, and water vapor which have been insignificant so far exert a bad influence on exposure processing, whereby a precise circuit pattern is not formed.
Hence, when at least the wafer is subjected to exposure processing, it is required that no impurities such as oxygen adhere onto the wafer. If only clean air is supplied as in prior arts, the adhesion of impurities onto the wafer can not be suppressed effectively since impurities such as oxygen are contained in the air, and moreover impurities adhering onto the wafer can not be removed.
The present invention is made in view of such a point, and its object is to provide a coating and developing treatment method and a coating and developing treatment system for preventing fine impurities at molecular level from adhering to a substrate such as a wafer.
To attain this object, a coating and developing treatment method of the present invention is a method for performing coating and developing treatment for a substrate, comprising the steps of: supplying a coating solution to the substrate to form a coating film on the substrate; performing heat: treatment for the substrate on which the coating film is formed; cooling the substrate after the heat treatment; performing exposure processing for the coating film formed on the substrate; and developing the substrate after the exposure processing, the method further comprising the step of supplying a treatment gas to form a treatment film on a surface of the coating film after the step of forming the coating film and before the step of performing the exposure processing for the substrate.
The step of supplying the treatment gas to form the treatment film on the surface of the coating film may be performed after the step of cooling the substrate after the heat treatment, may be performed during the step of cooling the substrate after the heat treatment, may be performed after the step of performing the heat treatment, or may be performed during the step of performing the heat treatment.
Furthermore, a coating and developing treatment system of the present invention is a coating and developing treatment system for performing coating and developing treatment for a substrate, comprising: a coating treatment unit for forming a coating film on the substrate; a developing treatment unit for developing the substrate; a thermal treatment unit for performing thermal treatment for the substrate; and a treatment gas supply unit for supplying a treatment gas to the coating film formed on the substrate to form a treatment film on a surface of the coating film.
It should be mentioned that the thermal treatment unit in the present invention implies a heat treatment unit, a cooling treatment unit, and a heat and cooling treatment unit.
According to the present invention, the treatment gas is supplied to form the treatment film on the surface of the coating film after the step of forming the coating film and before the step of exposing the substrate, whereby the substrate can be protected from impurities such as oxygen and water vapor in an atmosphere by this treatment film. Especially, if the impurities adhere to the substrate when the substrate is subjected to exposure processing, there is a possibility that the impurities absorb energy of a laser beam or the like used in exposure so that the exposure processing is not suitably performed. The aforesaid formation of the treatment film, however, enables suitable exposure processing. Further, the treatment film formed by the treatment gas is excellent in permeability, and permits a beam with a wavelength as short as about 157 nm to pass it. Accordingly, the adhesion of impurities to the coating film formed on the substrate is prevented while a predetermined circuit pattern can be precisely exposed onto this coating film.